High Resolution Sperm Selection by Peter Ahlering, MD


A Fact Sheet by Peter M. Ahlering, M.D., F.A.C.O.G.

With the process of in-vitro fertilization through ICSI, sperm are hand-selected at about a magnification of 500x. The sperm are selected based upon two criteria.

1. Motility, clearly we prefer to select sperm that are viable.

2. Morphology. Morphology is a description of size, shape, and physical assessment of the sperm based upon what we know to be “normal” or “textbook” appearance. When the sperm has a normal appearance according to what is referred to as the Kruger standard, then this correlates with sperm quality. In essence, “textbook” sperm is more likely to have chromosomal normality (euploidy) as well as to have less fragmented DNA. So, of course,morphology is the single most important factor that we use to select sperm.

Once the sperm are selected at 500 magnification, they were then set aside and subsequently injected into the egg through the process of ICSI. Thus, in essence, the process of ICSI involves two steps:

1. Selection.

2. Injection.

The process of sperm selection under magnification allows us to optimize sperm quality for the process of fertilization. In essence, also selecting the “best” sperm for subsequent injection minimizes the negative impact that sperm can have on an otherwise normal egg. This is in large part what we are trying to achieve through the process of ICSI: to remove the negative influence male factor can have on fertilization and subsequent embryo development in the process of IVF/ICSI.

Thus, of course, it stands to reason that improved ability to select sperm would translate into improved fertilization and subsequent embryo development. Then, of course, it stands to reason that improved embryo development would translate into improved implantation potential of an embryo and subsequent improved pregnancy rate/pregnancy outcome.
As such, optimizing sperm selection is crucial in the process of ICSI. Along this line, we have developed a system that is referred to HRSS (high-resolution sperm selection). With this technique, we are able to visualize the sperm under higher magnification at about 6000x. Utilizing this high magnification system, we optimize visualization of the sperm for the selection phase of ICSI. As noted, with this technique we were able to see fine morphologic details of the sperm that otherwise may go unnoticed in a lower magnification setting as done with traditional ICSI. In turn, we are able to more easily select “textbook” sperm, thus truly minimizing the negative impact that sperm can potentially have on otherwise normal eggs.

Indeed, the increased use of HRSS over the past three years in SIRM, St. Louis has shown to enhance positive pregnancy tests,  ongoing pregnancy rates and implantation rates versus the traditional process of ICSI. Early on, we focused on treating patients with multiple failed IVFs, multiple failed prior traditional ICSI procedures, and male factor couples. In this “high-risk” group of patients, we have seen an improved pregnancy rate, implantation, and ongoing pregnancy rate

(see data below). We believe that with continued use of this technique and broadening the application to a variety of clinical circumstances, we will continue to see improved pregnancy rates. The technique has unquestionably been shown to be safe and effective, in essence similar to traditional ICSI.


Peter M. Ahlering, M.D., F.A.C.O.G.

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